1. Field of the Invention
This invention generally relates to graphics systems, and more particularly to morphing data.
2. Related Art
Graphics systems are often used to generate and display images representing objects. A graphics system may store data representative of an object and display an image of the object using the stored data. Such data is also called object data or geometry data.
Morphing refers to changing the shape or appearance of an object. This can come about because of a change in the object, or because the viewer has changed position with respect to the object being viewed.
Often, a display is comprised of a plurality of objects. As an example, a view may consist of a horizon, two hills, and a bridge connected to bridge supports on the tops of the hills. At a distance, the hills may be barely visible, and the bridge may not be visible to the viewer at all. As the viewer xe2x80x9cmoves closerxe2x80x9d to the hills, the hills, the bridge supports, and the bridge become more visible. The location of each of the objects can be given with respect to the coordinate system of the display, both in the xe2x80x9cdistantxe2x80x9d view as well as in the xe2x80x9ccloserxe2x80x9d view, after it has been morphed. However, if the bridge supports and the bridge itself are described with respect to the coordinate system of the display, small errors in either the morphing equation or in the coordinates could result in discontinuities in the display. These discontinuities might appear as if, for example, the bridge were floating over the hill tops, rather than attached to them via the supports. The present invention addresses this problem. In the present invention, the horizon and the hills are morphed with respect to the coordinate system of the display. The bridge supports are then morphed with respect to the new positions of the hills, rather than the coordinate system of the display. In this manner, the bridge supports are xe2x80x9ctiedxe2x80x9d to the tops of the hills, and there will be no discontinuity in the display. Similarly, the bridge itself will be morphed with respect to the bridge supports rather than the coordinate system of the display so that it will be xe2x80x9ctiedxe2x80x9d to the bridge supports (which themselves are tied to the hill tops). This will eliminate the problem of the bridge xe2x80x9cfloatingxe2x80x9d over the hill tops.
The present invention provides a method and system for generating images by iteratively morphing objects from a reference appearance to a final appearance. In one embodiment, objects in the image are morphed sequentially, wherein each morphing is based on a previously morphed object. In a second embodiment, points along a Bezier curve are drawn through iterative morphing. In this embodiment, iterative morphing begins with a set of points or a polynomial from which the Bezier curve is derived.